[Qgis-user] Is QGIS showing the records with geometry NULL

[Paul Paris]

Hi Andrea,

Might something like:

    In the 'Select by Expression' dialog:

    $geometry = null

work?






On Thu, May 26, 2016 at 10:53 AM, Andrea Peri <aperi2007 at gmail.com> wrote:

> Hi jukka.
> I guess empty geometry is a not null geometry.
> Il 26 mag 2016 4:34 PM, "Rahkonen Jukka (MML)" <
> jukka.rahkonen at maanmittauslaitos.fi> ha scritto:
>
>> Hi,
>>
>> We spent some time with empty geometries in OpenJUMP and I attach some
>> test data from those experiments. Feel free to use it in the QGIS feature
>> request. Zip contains point, line, and polygon shapefiles, each having 8
>> features but only one feature with geometry.  From the WKT files you can
>> see that there are actually different kind of empty geometries. I even did
>> not bother to think about Z, M, and ZM geometries.
>>
>> POINT EMPTY
>> MULTIPOINT EMPTY
>> LINESTRING EMPTY
>> MULTILINESTRING EMPTY
>> POLYGON EMPTY
>> MULTIPOLYGON EMPTY
>> GEOMETRYCOLLECTION EMPTY
>>
>> One may say that empty is always just empty but one needs also to think
>> what happens if user copies POLYGON EMPTY and tries to paste it into a
>> point layer. Should copy be denied or empty geometry converted into POINT
>> EMPTY? For OpenJUMP that does not matter because it can handle all kind of
>> geometries on the same layer. However, saving POINT EMPTY into polygon
>> shapefile may fail and therefore OpenJUMP can convert even empty geometries
>> like POINT EMPTY ->POLYGON EMPTY.
>>
>> -Jukka Rahkonen-
>>
>> Andrea Peri wrote:
>>
>> Hi Jukka,
>> yes is exactly this the question.
>>
>> The QGIS don't show any record with null geometry so is impossible for me
>> to add a geometry to it. Or delete it definitivelly.
>>
>> But the record with null geometry is however saved when I export the
>> shapefile from qgis.
>>
>> So the QGIS show me 14 records but export a shapefile with 16 records
>> (2 records has null geometry).
>>
>> So when load it in a spatialite or on a postgis environment or open it
>> using another GIS like arcview3 from esri.
>> I see this two more records with null geometry.
>>
>> AFAIK this is a chaotic situation for who work using qgis and produce a
>> shapefile to distribute to other users that has other gis softwares.
>>
>> A.
>>
>>
>> 2016-05-26 10:24 GMT+02:00 Jukka Rahkonen <
>> jukka.rahkonen at maanmittauslaitos.fi>:
>> > Nicolas Cadieux <nicolas.cadieux at ...> writes:
>> >
>> >>
>> >>
>> >> Hi,
>> >> Is it possible that the 2 missing records were deleted in another GIS?
>> > There is an issue with deleting records in shape file as there are
>> > many ways to do that.  If the record were deleted in another GIS, they
>> > may show up (or
>> > not) in another software. Could that be it...
>> >> Nicolas
>> >
>> > Hi,
>> >
>> > I suppose that Andrea means a valid situation with real existing
>> > features which just do not have geometry. They are valid in shapefiles
>> > but many GIS software have difficulties in dealing with them.
>> > Naturally they cannot be showed on the map and spatial queries can't
>> > find them but they should be found from attribute view and be editable
>> there.
>> >
>> > -Jukka Rahkonen-
>> > _______________________________________________
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>>
>>
>> --
>> -----------------
>> Andrea Peri
>> . . . . . . . . .
>> qwerty àèìòù
>> -----------------
>>
>
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